Unauthorized access and information leakage caused by a cyberattack
株式会社メディア4u (a consolidated subsidiary of the filing company)
Administration console for the SMS transmission system provided by メディア4u
Cyberattack by a third party (unauthorized access)
Company response
An investigation in cooperation with external specialists, including determination of the cause and consideration of measures to prevent recurrence (no establishment of a third-party committee or special investigation committee is mentioned)
Strengthening the authentication infrastructure, introducing multifactor authentication, and strengthening access monitoring and detection systems, among other measures
Related procedures
Relevant supervisory authorities and third-party organizations (no specific names provided)
The company will proceed with identifying and blocking the intrusion route, taking security measures such as resetting authentication information and passwords for all customer accounts, conducting an investigation and determining the cause in cooperation with external specialists, reporting to the relevant supervisory authorities and third-party organizations, and implementing measures to prevent recurrence. Customers concerned will be contacted individually.
If new facts are identified as the investigation progresses, the company will provide an updated notice promptly. Details of the unauthorized transmissions will also be disclosed once they are known. Specific measures to prevent recurrence will be disclosed once finalized.
| Item | Details |
|---|---|
| Event name | Unauthorized access and information leakage caused by a cyberattack |
| Date of occurrence | 24 June 2026 (the date on which メディア4u confirmed the unauthorized access) |
| Date recognized / date notice received | 24 June 2026 (the date on which the unauthorized access was confirmed) |
| Subject Entity | 株式会社メディア4u (a consolidated subsidiary of the filing company) |
| Target Locations / Products | Administration console for the SMS transmission system provided by メディア4u |
| Cause | Cyberattack by a third party (unauthorized access) |
| Court or authority | Relevant supervisory authorities and third-party organizations (no specific names provided) |
| Investigation structure | An investigation in cooperation with external specialists, including determination of the cause and consideration of measures to prevent recurrence (no establishment of a third-party committee or special investigation committee is mentioned) |
| Measures to prevent recurrence | Strengthening the authentication infrastructure, introducing multifactor authentication, and strengthening access monitoring and detection systems, among other measures |
| Outlook | The company will proceed with identifying and blocking the intrusion route, taking security measures such as resetting authentication information and passwords for all customer accounts, conducting an investigation and determining the cause in cooperation with external specialists, reporting to the relevant supervisory authorities and third-party organizations, and implementing measures to prevent recurrence. Customers concerned will be contacted individually. |
| Planned follow-up disclosure | If new facts are identified as the investigation progresses, the company will provide an updated notice promptly. Details of the unauthorized transmissions will also be disclosed once they are known. Specific measures to prevent recurrence will be disclosed once finalized. |
Items this document does not state (14)
These are items the company does not state in this document. We do not leave them blank, nor fill them in from other sources or by inference.
The reasons the company gives
The company's own explanation, not something inferred from the numbers.Cyberattack by a third party (unauthorized access).